Giant Positive Magnetoresistance in Grain-Oriented CxCo1-x Alloys

The grain-oriented CxGo1-z (x = 0.9, 0.5) samples were fabricated by the hot.pressing method. The microstruc-ture was observed by an x-ray diffractometer and a scanning electron microscope. The resistance against the applied magnetic field was measured by a standard four-polnt probe method at different temperatures. The magnetoresistance and the magnetization ratio were studied as a function of magnetic field in the range of -1800 kA/m-1800 kA /m at different temperatures from 50 K to 300 K. The magnetoresistance of grain-oriented GxGo1-x is positive. The maximum positive MR of 98% at 50 K and 34% at 300 K was obtained under 1800 kA/m magnetic field in the C0.9Go0.1 sample.     

弛豫铁电体结构起伏与弛豫性研究

制备了铅基弛豫铁电体0.9Pb(Mg_1/3Nb_2/3)O₃-0.1PbTiO₃和Pb(Zn_1/3Nb_2/3)O₃基陶瓷. 铅基弛豫铁电体PMNT, PZN基陶瓷弛豫过程可用局域冻结模型描述. 在微畴-宏畴转变过程中, 弛豫铁电体产生结构起伏; 在相同的频率条件下, 弛豫铁电体的结构起伏程度越大, 弛豫程度越低. 在微畴-宏畴转变过程中, 随微畴的增大, 弛豫铁电体的弛豫特性减弱或消失.     

弛豫铁电体的微畴-宏畴转变与生长动力学

制备了铅基弛豫铁电体0.9 Pb(Mg1/3Nb2/3)O3-0.1 PbTiO3和Pb(Zn1/3Nb2/3)O3基陶瓷.利用修正的局域冻结玻璃模型研究了弛豫铁电体微畴-宏畴转变动力学和微畴生长动力学，结果表明,微畴-宏畴转变过程是量子化的过程，微畴-宏畴转变的驱动力主要是热驱动力和能量驱动力，微畴-宏畴转变稳定性由活化能和状态数来判断，而微畴生长动力学的稳定性可以用稳定性判据值大小确定.